How can secure a REST web service?

I am studying for the Spring core certification and I have some doubts related how REST web service and I am studying it to apply to Spring framework.

So I have some doubt related to this question founded on my study material but I can't find an answer.

So the questions are (I don't know it these questiona are related each other):

1. 
   

   Is REST secure? What can you do to secure it?

   
   


2. 
   

   Does REST work with transport layer security (TLS)?

   
   

I have understand how a REST webservice works and I know that it use the Http method to access resources and implement CRUD operation but what means asking if REST is secure? What is meant by secure in this specific case?

And what exactly is a TSL in REST?